Topographic Parameters Research Articles

A numerical study on the impact of lubricant rheology and surface topography on heavily loaded non-conformal contacts

The increasing requirement of high-power density (power throughput/ weight) in modern day machines lead to thin film lubrication condition in various machine components (rolling element bearings, gears, cams, etc,) due to severe loading conditions. Surface roughness features and lubricant rheology plays a vital role in thin film lubrication, and significantly affects the lubrication performance and lifetime of machine components. The present work demonstrates surface topography and lubricant rheology effects on the traction coefficient for heavily loaded non-conformal contacts. The load-sharing concept considering elastic-plastic deformation of asperities, and Carreau shear-thinning rheological model is employed to describe the dry rough contacts and non-Newtonian behavior of lubricant. An influence of surface topography parameters such as roughness, skewness, kurtosis, and pattern ratio on the traction coefficient is discussed. From results, it is found that among different surface topographies, negatively skewed surfaces having isotropic surface pattern exhibit minimum traction coefficient. The load share function and the critical rolling speed are determined for various surface topographies which provides further insights into the surface topography effect on traction coefficient. The findings of present study are noteworthy as they provide a theoretical basis for an assessment of the lubrication performance of heavily loaded non-conformal contacts.

Spatial and temporal patterns of near‐surface ground temperature in the Arctic mountain catchment

AbstractWe consider the case of a mountain catchment representative of southwest Spitsbergen to investigate the spatial and temporal variation in temperature of the near‐surface ground. We set up 20 thermistor strings distributed in different parts of the catchment, combine the measured data with land surface temperature (LST) retrieved from Landsat imagery, and verify the depth of ground thawing using electrical resistivity tomography. Under current climatic conditions, the thickness of the active layer (ALT) is at least 1.5 m, and in the lower parts of the catchment, between 3.5 and 4 m. The maximum ground surface temperature in the study area can be 27°C, and the temperature at a depth of 1.5 m, 5.4°C. We identified unfrozen ground (taliks) to a depth of 10–30 m in zones of water concentration at foot slopes and under river channels. The persistence of year‐round taliks at lake shores is possible. We verify the hypothesis that topographic parameters significantly determine the spatial variation of near‐surface ground temperature. For each level of temperature aggregation (from 6 h to 12 months data) and each examined the depth of the active layer, it is possible to identify environmental variables—related to energy conditions, heights, terrain relief, and ground surface moisture—significantly correlated with ground temperature, and consequently to specify multiple regression models. Topographic exposure and LST (used only in daily models), altitude, and various approximations of relative height are crucial in their construction. The ground temperature variance, unexplained in the regression analysis, prompts recognition of the critical role of factors not included in the modelling (groundwater, soil structure).

Correlations between the Topography-Induced Gravity, Terrain Structure and the Seismicity in the Gulf of Panama

This study presents new maps of the topographic and geophysical setting and seismicity in the region of the Gulf of Panama. The spatial analysis is based on the comparative analysis of the datasets on geoid, free-air gravity anomaly, topography and earthquakes. The cartographic framework is developed using the Generic Mapping Tools (GMT) scripting toolset. Seismic activity in the Central America is high due to the complex geologic setting, tectonic activity and lithosphere plate subduction. The data include the Earth Gravitational Model (EGM2008), the General Bathymetric Chart of the Oceans (GEBCO) and gravity grids. The seismicity data were collected from the Incorporated Research Institutions for Seismology (IRIS) catalogue on 1970–2021. The variations in data were compared to analyse correlations between the geophysical, seismic and topographic parameters. Free-air gravity, geoid and topographic data derived from the high-resolution datasets were used to investigate their effects on the main seismic sources in the region. The comparison of the maps showed that the distribution of the shallow earthquakes in the Pacific segment of Panama coincides with negative free-air anomalies and lower geoid values. The results revealed high values of geoid in the high mountainous regions of Panama (Cordilliera de Talamanca, southern coast of Peninsula de Azuero and eastern Panama, 77.5–78.5°W), which correspond to the topographic roughness in the highlands. Negative values of geoid are found over the Caribbean Sea basin (−4 to 0 m). The analyses of seismicity showed 1740 earthquake events varying by magnitudes from 2.9 to 7.8 at the depths up to 225 m (near the west coast of Colombia). A high concentration of the earthquakes is in the western region of the Panama’s shelf waters (~82–83.5°W), and on the border with Colombia (~77–78.5°W). High gravity anomalies (over 220 mGal) are found in the mountainous regions which match the geodynamic processes associated with the Earth structure and geodetic and geophysical effects. The regions of the high seismicity were defined in the Gulf of Chiriqui and eastern part of the Gulf of Panama.

Influencia de la longitud axial ocular en el grosor de la capa de fibras nerviosas peripapilar medido con tomografía de coherencia óptica

BackgroundOptical coherence tomography (OCT) allows the measurement of the peripapillary optic nerve fiber layer (RNFL) thickness. The effect of ocular axial length (AL) on RNFL thickness measurement may be relevant in the interpretation of OCT results in diagnosing optic nerve diseases. PurposesTo assess the influence of ocular AL on RNFL thickness and on optic disc topographic parameters (optic disc area, rim area and cup volume) measured by OCT, in healthy individuals. MethodA sample of 109 healthy eyes classified into three groups according to AL (A: AL <22mm; B: AL 22–24.5mm; C: AL >24.5mm) was studied. RNFL thickness and optic disc topographic parameters were measured using Swept-Source OCT Triton (Topcon Corporation, Tokyo, Japan) and were compared between groups using a variance analysis. Correlation between the AL and the study variables was performed using a Pearson's correlation coefficient test. ResultsThe RNFL thickness was lower in eyes with higher AL in the superior (r=−0.41; p<0.001), inferior (r=0.58; p<0.001) and nasal (r=−0.43; p<0.001) quadrants, in the mean value of the RNFL (r=−0.49; p<0.001), optic disc area (r=−0.40; p<0.001) and rim area (r=−0.25; p=0.01). ConclusionAL is negatively correlated with RNFL thickness and optic disc topographic parameters measured by Swept-Source OCT Triton (Topcon).

Online process monitoring of direct laser interference patterning using an infrared camera system

Direct laser interference patterning enables the fabrication of homogeneous microstructures in the sub µm range. Generally, the topography of fabricated structures is characterized ex-situ using for instance confocal microscopy or white light interferometry. These methods require at least few seconds to fulfill a measurement and therefore are not suitable for online process observation. In this study, an IR camera system is used for the first time, for capturing the average temperature during the DLIP treatment in real time. To determine a correlation between the average temperature and the topographical parameters, the treated surfaces are analyzed using confocal microscopy. A linear dependency between the applied laser fluence (in the range from 0.7 to 4.9 J/cm2) and the average measured temperature could be established. In addition, in this fluence range, significant changes in the surface roughness, skewness and kurtosis occurred, which could be associated to a certain process average temperature.

Evaluating the performance of machine learning methods and Geographic Information System (GIS) in identifying groundwater potential zones in Tehran-Karaj plain, Iran

Approaches based on Geographic Information Systems (GISs) are the most common and influential methods in identifying and mapping Groundwater Potential Zones (GWPZ). Moreover, employing Machine Learning (ML) algorithms in modeling the influencing parameters on GWPZ can improve the performance of these models. Therefore, the present study aims to assess the efficiency of ML methods, including Logistic Regression (LR), Random Forest (RF), Support Vector Machine (SVM), and Extreme Gradient Boost (XGB) models, along with influencing factors on GWPZ in GIS environment. Hence, the Tehran-Karaj plain in Iran, with approximately 5156 km2 area and relatively diverse elevations (818 to 4374 m), including flat and mountainous areas, was selected as the study area. Information from 105 wells was collected and divided into 75% for training and 25% for validation of the models. The effects of twelve parameters were investigated in three categories: topography, hydrology, and vegetation/geology (four parameters for each item). Moreover, LR, RF, SVM, and XGB models were applied to calculate the scores of each influential factor and create maps of GWPZ for the study area. Results of assessing the accuracy of GWPZ methods using the Receiver Operating Characteristic curve (ROC) revealed that the highest Area Under the Curve (AUC) value (89%) was obtained for the XGB model compared to RF, LR, and SVM models (with values of 87.4, 76, and 75.3%, respectively). Moreover, XGB and RF show higher Kappa coefficient values, with the values of 80% and 65%, respectively. This indicated the tree-based models' high performance (i.e., XGB and RF) compared to other models. Model outputs also demonstrated that topographic parameters (i.e., altitude levels and slope) strongly influenced the GWPZ predictions of the used models in the study area. In general, results indicated the high performance of ML algorithms and GIS for identifying GWPZ.

Influence of the Chemical Composition and Topography of the Ti6Al7Nb Surface Etched in Fluorine Plasma on Its Selected Properties

Herein, a new way of the surface modification of Ti6Al7Nb alloy in fluorine plasma is presented using the mask made of stainless steel and its influence on the selected properties, including chemical composition, topography, and tribological ones. Depending on the etching process parameters, different characteristics of the surfaces are obtained. The higher is the value of the negative bias, the less fluorine concentration on the etched surface and higher etching rates. Etching using the SF6 gas shows bigger etching rates in comparison to the etching using the CF4 gas. Chemical composition of the modified surfaces shows greater impact on tribological characteristics than topography parameters. The lowest wear rate is observed for the sample modified using the CF4 gas.

Assessment of ambient dose equivalent rate distribution patterns in a forested-rugged terrain using field-measured and modeled dose equivalent rates

Measuring radioactivity in forested mountainous areas is challenging owing to the limited accessibility on foot and the canopy blocking of airborne survey signals. Meanwhile, the influence of multiple environmental factors on radioactivity, in particular on ambient dose equivalent rates (ADER) in a forested area, are not well understood. In this study, we surveyed the ADER using hand-held and backpack-type scintillators in a forest of deciduous and evergreen trees in Iitate Village, Fukushima Prefecture, Japan, on multiple dates. The village is located 35 km northwest of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP). The observations showed that, 7.5 years after the FNDPP accident, the ADER still exceeded the maximum permissible level (0.23 μSv h−1) of the Japanese standard limit. The ADERs were distributed unevenly in the forest, ranging from 1 μSv h−1 to 3.73 μSv h−1, with statistically significant variabilities among survey dates. The spatial variabilities of the ADER among the survey dates were depicted by semivariograms. The effects of the complex topography on the ADER were examined using multivariate adaptive regression splines against five selected topographic parameters. Although the topographic effect of individual parameters varied between survey dates, when all topographic parameters were considered, the model predictions yielded a positive correlation (R2 > 0.54). We discovered ground wetness as the source of ADER variations among survey dates based on climatic records. Additionally, we estimated the ADER from radiocesium concentrations in soil samples and checked their consistency with the measured ADER. It was found that about half of the ADER estimated from the soil samples were within the range of field measurements. Although challenges remain in the modeling of radioactivity pathways under natural conditions, this study shows that combining topographic features, meteorological factors, and near-ground and high-altitude surveys are the keys to understanding radiation behavior in the environment.

Empirical relationship for the estimate of pyroclastic soil thickness using slope steepness

The assessment of soil thickness plays a primary role in different areas of the geosciences, including landslide hazards and soil erosion assessment. Nevertheless, the thickness of the cover deposits is difficult to measure over large areas while the prediction with numerical models is still challenging. In this study, some topographic attributes, namely slope angle and profile curvature, are investigated as proxies for the estimate of soil thickness of pyroclastic cover through empirical relationships. The study area is the North-facing slope of the Lattari Mts. (Campania, Southern Apennines), which were historically affected by several flow-like landslides and flash floods. The dataset was collected with both direct and indirect measurements from field surveys and investigations in two test sites of the study area.The topographic parameters were derived from DEMs at three different cell sizes, respectively at 1 × 1 m, 5 × 5 m, and 10 × 10 m. The slope angle at 5 × 5 m resulted in the most fitting parameter with the soil thickness, whereas the curvature showed a low correlation at all the investigated scales. The relationship for the Pyroclastic Thickness Estimation (PTE) is defined by an exponential law, which was validated by an internal and external dataset and checked against other predictive models used in the literature for similar study areas.

Nanomechanical changes in probiotic bacteria under antibiotics exposure: Implications on Lactobacillus biofilm formation

Recognition of the microbial cell's surface constituents' biophysical properties is an important research topic, allowing a better understanding of the cell's behaviour under different conditions. Atomic force microscopy (AFM) was employed in this study to analyse the basis of the nanomechanical changes in probiotic bacteria under nitrofurantoin, furazolidone, and nitrofurazone exposure. Recorded significant changes in the two Lactobacillus strains cells morphology, topography, and adhesion parameters resulted in the increase of the cells' longitude (up to 2.58 μm), profile height (by around 0.50 μm), and decrease in the adhesion force (up to 13.58 nN). Young's modulus and adhesion energy decreased within 96 h, however with no negative effect on the cells' morphology or loss of structural integrity. Observed modifications present the mode of action of the 5-nitrofuran derivative antibiotics on probiotic biofilm formation and suggest activation of the multilevel adaptation mechanisms to counteract unfavorable environments. A visual change in bacterial morphology such as an increased surface-to-volume ratio might be a link between molecular-level events and outcomes in individual cells and biofilms. This paper for the first time shows, that these antibiotics affect the properties of non-target microorganisms as lactobacilli, and might impair biofilm formation. However, the degree of such transformations depends on the delivered active substance.

Connection stiffness modeling of rotating dovetailed blade with macro-micro interface topography

The connection stiffness between the dovetailed blade and disk indicates the boundary condition of the blade, directly influencing the dynamic response of the blade-disk assembly and even the structural safety of the whole aero-engine. Due to the limited manufacturing precision, the contact interface of dovetailed joint is rough with macroscopic geometrical deviation inside. However, few researches are reported about the effect of macro-micro interface topography on the connection stiffness. In this paper, a stiffness model of the rotating dovetailed blade with interface topography characteristic is proposed. First, a statistical contact model is established to describe the normal and tangential contact responses of the rough interface in dovetailed joint. Then, by introducing the displacement and angle infinitesimals, the explicit expressions of the connection stiffnesses in different directions are derived out. Finally, based on the presented connection stiffness model, rotational speed, working temperature, macroscopic geometrical deviation, and microscopic topography parameters are investigated in detail. The results show a great influence of interface topography and operating parameters on the connection stiffness. The work in this paper provides a novel way to reveal the inner mechanical relationship between the macro-micro topography and the connection stiffness of dovetailed blade under the work condition, which is meaningful for the actual manufacturing and performance analysis of the aero-engine.

Evaluation of corneal topography and higher order aberrations of the fellow eye in unilateral keratoconus

Purpose To assess parameters of corneal topography and higher order aberrations (HOAs) data in the apparently normal contralateral eyes of unilateral keratoconus (KC) cases in comparison with normal eyes of healthy individuals. Patients and methods This observational case-control study included 70 eyes divided into two equal groups; group A was the fellow eyes of unilateral keratoconus patients and group B included the normal control eyes. They were examined by Schimpflug camera to extract the study parameters (keratometry indices, the inferior-superior(I-S) difference at 4 mm, posterior elevation (PE), front and back difference, thickness progression index, corneal pachymetry, multimetric D index (D index), topometric indices and Zernike analysis). Results In comparing the study data between Groups A and B, we demonstrated that ISV, IVA, and CKI had no difference between the two groups. But other topometric parameters showed statistically significant differences between the two groups. Assessment of corneal aberrations revealed that the RMS HOA, vertical coma, and spherical aberrations were associated with significant increases in the apparently normal eyes of unilateral KC cases in comparison with healthy individual eyes (P&lt;0.001). Conclusion Fellow eyes of unilateral KC cases seem not to be totally normal. And so, it is recommended to regularly examine these eyes at close intervals to catch up any abnormality and to avoid KC progression.

Fatigue life estimation of TMT reinforcing steel bar considering pitting corrosion and high temperature impacted surface topography

Surface topography of steel changes considerably when subjected to pitting corrosion and high temperature leading to a reduction in its fatigue life. Based on experiments, including microstructural studies and employing multiple linear regression methods, prediction models for surface topographic feature parameters such as arithmetic mean height, total height, ten-point height, profile mean spacing as a function of pitting severity, corrosion level severity, and temperature are developed. Using identical parameters, prediction models for surface topographic feature variable in stress concentration factor and defect size parameter are also developed. Further, a framework for estimating high-cycle fatigue life is proposed, incorporating the developed models. The proposed framework is validated by comparing the fatigue life estimated by incorporating the developed models with experimental data from the literature.

Mechanism analysis of internal solitary waves breaking encountering submarine ridges based on laboratory experiments

Internal solitary waves are commonly present in global oceans, and these waves encounter submarine ridges during their propagation, resulting in breaking. In this study, a two-layer fluid model and the gravity collapsing method were used to simulate the breaking process of internal solitary waves encountering submarine ridges in the laboratory, and particle image velocimetry was used to monitor the flow field. Based on the different roles of motion mechanisms in the wave-breaking process, the breaking types were classified. Moreover, the relationship between the topography, the initial parameters of internal solitary waves, and the breaking types was studied, and the movement parameters during the wave-breaking process were analyzed. The experiments showed that the Iribarren number and Bisw parameter proposed based on the gentle slope breaking process could not effectively classify the breaking types when internal solitary waves encountered submarine ridges because the permeability of the submarine ridges was different from that of gentle slopes, which significantly affected the motion mechanism during the breaking process. The movement parameter γ clearly reflected the roles of different motion mechanisms during the wave-breaking process. Another parameter δ established the relationship between the motion mechanisms and the topography and initial wave parameters.

Detection of invasive plants using NAIP imagery and airborne LiDAR in coastal Alabama and Mississippi, USA

Invasive plants have imposed severe threats to native ecosystems worldwide. Triadica sebifera (Tallow tree) and Ligustrum sinense (Chinese privet) are among the most prolific invasive species in the southern United States (US) that needs urgent assessment to protect coastal ecosystems. The lack of spatially explicit assessments of these invasives, coupled with the increasing availability of high-resolution remotely sensed data, represents an opportunity to produce a distribution map for subsequent monitoring. The overall goal of this study was to develop spatially comprehensive maps of Tallow tree and Chinese privet in ecologically sensitive coastal regions, where both invasives have become well established. The study was conducted in three coastal sites within Alabama and Mississippi: (1) Mobile Tensaw River Delta, (2) Bon Secour National Wildlife Refuge, and (3) Mississippi Sandhill Crane National Wildlife Refuge. We implemented three image classification methods, representing unsupervised, supervised, and machine learning techniques, respectively: (1) ISODATA, (2) Maximum Likelihood (ML), and (3) Random Forest (RF). For each classification, a 1 m National Agriculture Imagery Program (NAIP) orthoimage was first examined, then integrated with vegetation structure and topography parameter derived from airborne light detection and ranging (LiDAR). The maximum Overall Accuracy (OA) of 87.5% was obtained using RF model with NAIP stacked image integrated with LiDAR derived variables. Overall, findings highlight the potential for accurately characterizing both Tallow tree and Chinese privet using readily available remote sensing data. Mapped products from this study represent a spatially comprehensive baseline inventory of crucial invasive species and will serve to inform the development of a framework for broader-scale mapping and monitoring efforts.

On the Biotribological Surfaces of Dental Implants: Investigation in the Framework of Osseointegration

In the last decades, the use of dental implants has been growing exponentially, but some clinical issues such as inflammations, infections or mechanical complications like fractures or implant loosening, are still open, leading to a failure and implants' revision surgery. Many researchers state that one of the main reasons is certainly due to a not complete or stable implant osseointegration respect the surrounding bone. As stated in literature the formation and the growth of the bone in contact with the implant is strictly correlated with the micro topography of the implant contact surfaces, because of the biotribological, biological and chemical interactions occurring on the surface. To date, however, only arithmetical roughness is reported in the most part of investigations as a valid surfaces' topographical parameter which could be correlated with osseointegration. Moreover, a consolidated and standardized procedure for dental implant surface measurements is not established. Hence, the aim of this investigation was to propose an advanced methodology for analyzing dental implant surfaces based on optical measurements and accurate data processing, and to discuss the results obtained on a real implant, in the framework of osseointegration and biotribological contact literature findings. With reference to a commercial dental implant, the topography was accurately achieved by an optical confocal and interferometric apparatus and then post processed to obtain all the quantities necessary for the contact surface accurate description discussing the role of the topographical quantities on the influence of bone/implant contact/osseointegration phenomena. Height, spatial, hybrid and functional parameters were presented for both waviness and roughness profiles providing significant discrepancies in most of the roughness values. On the other hand, the additional specific investigations such as surface isotropy or particle analysis may yield the basis for a novel protocol of surfaces topographical characterization procedure in dentistry.

Ocular axial length influence on peripapillary retinal nerve fiber layer thickness measurement with optical coherence tomography

BackgroundOptical coherence tomography (OCT) allows the measurement of the peripapillary optic nerve fiber layer (RNFL) thickness. The effect of ocular axial length (AL) on RNFL thickness measurement may be relevant in the interpretation of OCT results in diagnosing optic nerve diseases. PurposeTo assess the influence of ocular AL on RNFL thickness and on optic disc topographic parameters (optic disc area, rim area and cup volume) measured by OCT, in healthy individuals. MethodsA sample of 109 healthy eyes classified into 3 groups according to AL (A: AL<22mm; B: AL 22−24.5mm; C: AL>24.5mm) was studied. RNFL thickness and optic disc topographic parameters were measured using Swept-Source OCT Triton (Topcon) and were compared between groups using a variance analysis. Correlation between the AL and the study variables was performed using a Pearson's correlation coefficient test. ResultsThe RNFL thickness was lower in eyes with higher AL in the superior (r=−0.41; p<0.001), inferior (r=0.58; p<0.001) and nasal (r=−0.43; p<0.001) quadrants, in the mean value of the RNFL (r=−0.49; p<0.001), optic disc area (r=−0.40; p<0.001) and rim area (r=−0.25; p=0.01). ConclusionsAL is negatively correlated with RNFL thickness and optic disc topographic parameters measured by Swept-Source OCT Triton (Topcon).

Influence of Cutting Parameters and Tool Geometry on Topography of Hard Turned Surfaces

Three-dimensional topography measurement is a focus area of precision machining because it provides detailed information on the functional behavior of contacting surfaces. The purpose of this study is to analyze how the process parameters and the edge geometry of the cutting insert influence the topographical characteristics of hardened 16MnCr5 steel surfaces and to determine the favorable combinations of technology parameter values based on the analyzed topography parameters (Ssk, Sku, Sz, Sa, Sk, Spk, Svk). A research question is whether the analyzed parameters can be substituted by each other or not. A hard turning experiment was carried out based on a full factorial design of experiments, and the areas of the machined surfaces were scanned and analyzed by analysis of variance, regression analysis (response function), and correlation analysis. It was found that there are strong correlations between the topography parameters that allow the substitution of one with another; the main influencing cutting parameter is the feed rate for both insert types. The contributions of the study are the numerical information with regard to the correlations among the topography parameters, as well as the extent of the influence of cutting parameters.

Experimental Investigation of Tribology-Related Topography Parameters of Hard-Turned and Ground 16MnCr5 Surfaces

Several surface topography parameters are available for the quantification of tribological properties of machined surfaces. Although these parameters and their influences are widely studied, there are contradictory findings due to the nature of the topography parameters, i.e., the behavior of different materials and cutting tool interactions lead to relatively varying numerical results. A comprehensive study of these interactions can contribute to more exact industrial machining applications. In this study, tribology-related 3D topography parameters of hard-machined (hard-turned and ground) surfaces were analyzed. The machining experiments were carried out based on a detailed design of the experiment; the analyzed material was case-hardened low-carbon content steel, which is widely used for automotive, industrial components such as bearings or gears. From the topography data, response function, correlation, and relative deviation analyses were carried out for the analyzed topography parameters, and tribology maps were created to support the selection of optimal cutting parameter values.

Safety and Efficacy of Corneal Cross-Linking in Patients Affected by Keratoconus: Long-Term Results.

The present study evaluated the effectiveness and safety of corneal collagen cross-linking (CXL). A total of 886 eyes with progressive keratoconus were enrolled in a retrospective cohort study in a tertiary care university hospital. CXL was performed using a standard epithelium-off Dresden protocol. Visual outcomes, maximum keratometry (Kmax), demarcation line measurements, and complications were recorded. Visual outcomes and keratometric data were analyzed in a subgroup comprising 610 eyes. Uncorrected distance visual acuity (UDVA) improved from 0.49 ± 0.38 LogMAR to 0.47 ± 0.39 LogMAR (p = 0.03, n = 610) three years after the procedure, while corrected distance visual acuity (CDVA) improved from 0.15 ± 0.14 LogMAR to 0.14 ± 0.15 LogMAR (p = 0.007, n = 610). A significant reduction of Kmax from 56.28 ± 6.10 to 54.98 ± 6.19 (p < 0.001, n = 610) was observed three years after CXL. In five eyes (0.82%, 5/610) keratoconus progression continued after CXL. Three eyes were retreated successfully with documented refractive and topographic stability after five years. In the 35 eyes that completed 10 years of follow-up, mean visual acuity and topographic parameters remained stable. In conclusion, CXL is a safe and effective treatment for avoiding keratoconus progression. Long-term data are encouraging, supporting a high safety profile for this procedure.